Adjustment system



N R um Aug, 6, E946 M w @msm ADJUSTMENT SYSTEM Filed May 5, 1942v 5Shee'ts-Sheet l Au@ 653946 I M. w. @All lsER 23405439 ADJUSTMENT YsTEMFiled May 5, 1942 3 Sheets-Sheet 2 :Snventor mi@ @9 m@ M. W. GAESERADJUSTMENT SYSTEM I Filed May 5, 1942 3 sheetssneei 3 maentor www www@megs Patented Aug. 6, 1946 ADJUSTMENT SYSTEM Martin W. Gaiser, Kokomo,Ind., assgnor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Application May 5, 1942, Serial No. 441,825

(Cl. Z50-40) 13 Claims. l

This invention relates to means for measuring given electrical valuesand utilizing said measurements for predetermined adjustments. Morespecifically it relates to means indicating a reversal in rate of changein voltage or in the directional flow of current in a circuit to enableadjustment at a given optimum value. There are a number of instanceswhere it has been found desirable to ascertain the exact point at whichvoltage flowing in a circuit ceases to increase and begins to decreaseas the values or quantities of the various elements composing thecircuit are varied. This may be termed finding the peak or resonancepoint of a circuit. There are many instances in which Such means mightbe advantageously employed and as one example there is shown in thefollowing specification the use of such a peak relay or indicator usedin adjusting an intermediate frequency transformer assembly toa setpredetermined frequency automatically which is then assembled into aradio receiver. It is to be understood that this is merely forillustrative purposes and should not be considered as limiting thebroader aspects of my invention.

These intermediate transformer assemblies mentioned above arefactory-adjusted or tuned be tuned to the same resonant frequency topass a maximum amount of power from the output of the rst detector ormixer tube to the second detector in a conventional receiver. Physicallythese coils are wound on a common form and mounted on -a base with twotrimmer condensers which are small spaced plates separated by adielectric, one plate being adjustable with respect to the other bymovement of a small screw. These trimmer condensers are so mounted onthe base that these adjustable screws are accessible for adjustment, thewhole assembly forming a unitary part for insertion into the receiverchassis after the two circuits have been accurately tuned to theintermediate frequency of the set for which it was designed.

It is therefore an object of my invention to provide means forascertaining or determining the resonant condition of an electricalcircuit.

It is a further object of my invention to provide means forautomatically peaking or adjusting a circuit to its resonant condition.

It is a still further objectl of my invention to provide means forautomatically adjusting an intermediate frequency transformer to apredetermined resonant frequency before insertion lnto a radio receiver.T

It is a still further object 'of my invention to provide such automaticmeans for adjusting a resonant circuit which 'will be simple inoperation and will not easily get out of adjustment.

With these and other objects in view, which will become apparent as thespecification proceeds, my invention will be best understood byreference to the following specification and claims, and theillustrations in the accompanying drawings, in which:

Figure 1 is a side elevation showing the adjusting means of myinvention;

Figure 2 is an enlarged detailed sectional View taken on line 2'-2 ofFigure 3 through the screw driving means for adjustment;

Figure 3 is a top plan View partly in section taken online 3-3 of Figure1;

Figure 4 is an enlarged sectional view through the gear driving means;and

Figure 5 is a schematic wiring diagram of the system of my invention.

Referring now more `specifically to the drawings, in Figure l there isprovided a suitable base 2 which supports thereon a test block 4which'is adapted to support devices to be adjusted such as intermediatefrequency transformers mentioned above. These transformers are usuallyobtained in the shape of a small rectangular metallic container ofsubstantially square cross section having somewhat the appearance of asmall tube. Extending from one end of this container there are usually aseries of connecting wires, such as shown in dotted lines in Figure 3 at6, 8, lil and I2, which extend from the coils and condensers within themetallic container and are clipped under suitable connecting clips I4,l, i8 and 20, the metallic container itself lying betweensuitableprojections `on the upper surface of the testing block 4.

As will be seen in Figure 3, this test block 4 may be pivoted around itscenter and in this manner one transformer assembly may be in the processof being adjusted While another is being placed in the opposite end tobe ready for adjustment when the first has been completed. After the newtransformer has been inserted in its test position, the test block isrotated about its pivot and the transformer then assumes a position asshown in dotted lines in Figure 3 in front of the two motor-driven screwdrivers whose purpose it is to engage the adjusting screws and to bringthem to the proper position of resonance at a predetermined frequency.

Each of the adjusting screws in the transformer is adapted to be engagedby a separate and independently driven screw driver which is adapted tofit into the slotted end of the screw. The projecting portions of eachof these screw drivers are supported in a suitable bracket 22 whichcarries a plurality of horizontal sleeves 24 in spaced relation, saidsleeves telescopically carrying therein a second hollow sleeve 26 whichcarries on its forward end a hollow metallic cup-shaped member 28. Thiscup-shaped member has an opening 38 through its base through whichprojects a stud 32 threaded into the end of the member 26 for supportingthe cup member 28 on said end.

Within the cup 28 is a sleeve 314 of resilient insulating materialwithin which is carried the screw driver 38 per se, which it will-beseen is fully insulated from its supporting screw by the insulatingsleeve 34 and a small insulating pad 36 between thereto, but rotateswith the cup member 28 whenever the same is driven by suitable means tobe described. The inner end of the screw driving member 38 is hollow, asshown at 40, and also has a small bore 42 extending out to its frontportion. Within this bore and carried back into the hollow section 48 isa protruding pin member 4Q which has a disc-like portion 46, the latteracting as one end stop for and compressing a resilient spring member 48between itself and the base of the opening 40. This tends to expel thepin 44 from the forward face of the screw driving member 38 which isbrought to a driving tip 50. It therefore serves the function of alocating pin, and when the tip 50 proceeds into the groove in a screwhead, will of course be pushed back so that it will be flush with thetip of the screw driver. The function of the projecting pin 44 orlocating pin is that when the screw driving assembly is moved up tocontact the adjusting screw on the base of the transformer, it will tendto locate or find this groove, and when it does fall into the same, willbring in or guide the screw driving tip 58 into the proper groove.

The member 28 is secured, as before stated, by the stud 32 to theforward end of the member 26, but this construction is resilient to theextent that there is provided a coiled spring 52 located between thehead of the stud 32 and the base of the member 28 which tends tomaintain the cup 2B forced against the end of the member 28 under normalconditions, but allowing it a certain amount of eccentricity.

The hollow portion of the member 25 carries therein a cylindrical member54 which is directly connected to the end of a flexible drive member 64which is driven from a prime source of power. This member 54 has a slot58 therein in which rides a pin 50 carried by the member 2G from oneside to the other. This pin and slot connection enables considerablelongitudinal movement between the twomembers 54 and 26, but assures thatrotary or driving connection between the two is provided at any of thelongitudinally adjusted positions. There is also provided in thisinstance a helical spring 62 which presses against cylindrical bearingplug 16. The end of the driving cable terminates in a connecting tongue'I8 adapted to fit within a slot 80 in the end of a drive shaft 82. Along sleeved member 84 is mounted upon the shaft 82 at its opposite endand extends for substantially one-half of the total length of the shaft.This sleeved member carries a suitable ball bearing support 86 which ismounted within the opposite end of the cylindrical opening 14. Thissleeve member 84 may rotate with respect to the shaft 82, the shaft 82projecting from the end of the sleeve and having therethrough a C-washer85 to prevent the expulsion of various parts carried by said shaft.

Intermediate the two ends of the shaft there is secured thereto a collar88 adjacent the cylindrical bearing plug 16, and also a movable clutchcollar 90 which has diametrically opposed slots $2 therein which areadapted to provide an opening for a pin 94 which extends through theshaft, thus providing means whereby the clutch member 98 may slidelongitudinally of the shaft, but always turn with the same. The face ofthe clutch collar S8 is provided with diametrically opposed grooves 92therein which are adapted to be engaged by extending tips 95 carried bythe adjacent face of the sleeve member 84, thus providing a clutchdrive.

Adjacent the inner end of the clutch member 90 is a washer 96 andbetween this washer and the member 88 and concentric with the shaft is ahelical spring 88 which bears against the two members and tends to keepthe clutch collar 88 in its left-hand or clutch engaging position as 1shown in Figure 4. Mounted on the end of the shaft 82 which projectsinto the main chamber of the gear box isa bevel gear |08 which isrigidly secured to the sleeve member 84. Any driving force thus appliedto the bevel gear |58 is transmitted through the sleeve 84, clutchmembers 93 and 95, pin 94 to the drive shaft 82. The purpose of thisclutch arrangement will be described more in detail at a later point.This same construction of course applies to the opposite drive for thesecond screw driver which is housed within the housing portion 'l2 whichin turn terminates in a bevel drive gear |82 on the inner end of thatassembly.

Extending directly across the main portion of the gear box E8 is a mainshaft |04 which i's trunnioned at one end in a ball bearing assembly 06and vin the opposite end in a second ball bearing assembly |88, theouter projecting end. of which has thereon a pulley ||0 adapted to bedriven by a V belt H2 from some suitable source of power such as themotor |14.

Mounted upon this shaft |84 at one side is a sleeve member 6 which iskeyed to the shaft .by slots ||8 and |28 having therein small balls |22.Thus this sleeve may be slid axially of the shaft, but caused to rotatetherewith at all times. At its center this sleeve Yhas an indentedgroove |2fi in which there rides a pin |26 mounted upon one end of apivoted lever |28 which is pivoted at |30 and carries at its outer endan operating spring |32 which is formed in the general shape of ahairpin, between the two portions of which projects a pin |34 mountedupon a slidable bar |36 whose position is determined by the energizationof certain operating coils |38 and |40. Mounted upon this sleeve ||6 andon opposite sides of the groove |24 are two bevel gears |42 and |44which are rigidly secured thereto by suitable set screws. These gearsare spaced at such an interval that the bevel gear |00 extends downbetween them but does not contact either, it being necessary to moveeither upwardly or downwardly as shown in Figure 4 to form a drivingconnection between |00 and |42 or |44. Thus it will be seen that in theposition shown no driving exists between the shaft |04 and the shaft 82.However, if either of the electromagnets |38 and |40 is energized tocause the sliding member |36 to move, the spring |32 will cause thelever |28 to pivot and to move one or the other of the gears |42 or |44into engagement, and if the shaft 04 is rotating, such rotation will 'betransmitted to the shaft 82. The same construction prevails for drivingthe opposite gear |02 which in this instance may mesh with bevel gears|46 or |48 which are mounted upon a sliding sleeve |50 controlled by theposition of a pivoted lever |52 which in turn maybe moved byvelectromagnets |54 and |56.

Thus when the motor ||4 is energized, the shaft |04 is rotated, and bycontrolling the energization of the four electromagnets |54, |56, |38and |40, either of the screw driving members may be rotated in eitherdirection. From th above description it.will be obvious that there isherein provided a pair of motor-driven screw driving means which arecapable of rotating in either direction to turn the adjusting screws ofthe trimmer condensers in a transformer assembly. -In order to start ata given index, it has been found desir-able to turn the screw varyingthe condenser to one limit so that the condenser will be at one definitelimit of its capacity value, and therefore in actually operating .theapparatus the driving means is brought into engagement with the slottedscrew head and driven until the screw reaches one limit of travel. Y

At Ythis point the force being applied by the gear |00 or |02, and whichis transmitted to the screw driving head, must find some means ofrelease due to the fact that the screw stops turning. This isvprovidedby the clutch arrangement S3 and 05 which are the projecting and groovedportions ofr the adjacent associated membersl 90 and 84, VThus asdriving force is applied to gear |00, the sleeve member 84 will continueto rotate, Y

but the grooved and tongue members -83- and^05 will slip over each otherand the shaft 82 will not rotate, Thus when the screw driver itselfstops, the clutch member will slip and while the main drive shaft |04continues to rotate, no parts will be broken and this will cause alongitudinal movement of the clutch member 90 lengthwise of the shaft82. This lengthwise movement will cause the closure of a switch later tobe described.

Referring now more specifically to Figure 5 which is a circuit diagramof the various connections of my invention, there is therein shown astepped switching arrangement designated generally at A. This switchingmeans is a ratchetV step-by-step switch having a plurality of contactarms which are moved around circumferentially upon a stepping by thecontrol relay. It has a number of different contact'pointsand fourswitch arms, namely, |60, |62, |64 and |66, each of which rotates onecontact position upon an actuation of the ratcheting or driving means.An electromagnet |68 is provided for actually ratcheting the means anddriving the rotating switch arms. There is also provided a secondelectromagnetic means |10 which releases the switch arms when they havecompleted their movement over a certain number of the switch points landallows them to return'by'spring pressure to their initial position whichis that shown, namely, with switch arm |60 contacting switch pointswitch arm |62 contacting switch point and switch arm |64 contactingvswitch point I3. In this Darticular instance switch arm |66 merely actsas an auxiliary spare and is not utilized.

In the upper right-hand portion of the diagram is more orlessschematically shown the screw driving means which has previouslybeen discussed in detail and in this instance the two screw drivers arereferred to asv S and P, screw driver P being driven by gear |02 whichmay mesh with drive gears |48 or |46 and screw driver S being driven'bygear |00 which may mesh with drive gears |42 or |44, these meshingsbeing controlled by the electromagnets |54, |56, |38 and |40 aspreviously described. The motor |4 is shown at M. There is also providedmeans for retracting the two screw driver tips and this is showndiagrammatically as a cross bar |12 which is secured to the movablesections of ,both S and P and whose position is regulated by anelectromagnet |14 whose armature is connected to the cross bar.

n There is also provided a switching means, such as diagrammaticallyshown at |16 and |18, associated with the clutch members 90 `ofveachassembly whereby whenthe clutch slips at one eX- tremity of travel ofthe adjusting screw, a circuit will be made to actuate certain necessaryapparatus to be described. There are also shown on this diagram a seriesof operating relays, Whose armature |82 operates switches |84. and |66,relay |88 whose armature |00 gaps a switching means |62, a relayV |94whose armature |66 controls one switch |08 in its lower position, and asecond switch 200v in its upper or actuated position. The power supplyis connected to the two incoming lines 202 and 204 in the latter ofwhich is a main switch 206.

Tapped from the incoming line is a transformer primary 208, thesecondary of which is formed of a pluralityof coils 2| 0, 2|2, 2|4 and`2|6 which supply vdifferent voltages for the amplifying means and theremainder of the system. A second transformer primary 2 I8 also has aplural coil secondary 220 for supplying additional voltages as desired.Any desired source `of modulated radio frequency is applied across theterminals 222 and 224 for test purposes. This input is applied to thevacuum tube VV1 the output of which is applied to the intermediatefrequency transformer being tested which is shown within the dotted linesquare immediately to the right of V1 and indicated as 226.

The output of the intermediate frequency transformer is connected to apair of amplifiers V2 and V3 and the output of these two amplifiers is'connected to a transformer 228 across the primary of which is connectedanY indicating meter 230. The output of the transformer 228 is con.-vnected to a Thyratron tube V5 which is in this instance the actualdetector ofthe peak or resonant point to be determined and the controlvoltage in this instance is developed across the resistors 232 and`234and the capacitor236. The

input circuit to the grid of the tube V is controlled by a relay 238whose armature controls two movable switch points: 240 oscillatingbetween xed switch points 242 and 244 and 24S cooperating with a switchpoint 248.

From an intermediate point between the two resistors 232 and 234 thereis tapped a line 250 which extends to a resistor 252 and thence to acapacity 254 which acts as a time delay in a given control circuitthrough line 256 back to control resistors 258 and 260 in the input totube V1. There is also provided a differentiating circuit which consistsof a condenser 262, resistor 264, and a small resistor 266 across thebias grid supply of the tube V5. The tubes Va and V7 are merelyrectifier tubes which are fed by the transformers 208 and 2|8 andadapted to provide the necessary D. C. voltages at predetermined pointsin the system. i There are provided at certain predetermined points inthe system a plurality of condensers 268, 210, 212, 214 and 216 whichare placed in the circuit to limit current or voltage surges which mightaffect the operation of the Thyratron V5 when various solenoids areoperated, but these are not large enough to bypass a sufficient amountof current so that any solenoid will be energized unless directconnection is made to it. If the power supply is closely regulated andcertain shielding is employed, these condensers may be omitted. Not allof the lines are shown connected to the various sources of power inorder to simplify the drawings. For example, the lament circuits of thevarious vacuum tubes are not shown connectedto a source of power and aremerely terminated in an arrow. This is also true of certain of the relaycircuits and wherever in the ldrawings an arrow is applied, it merelymeans that a suitable source of voltage is connected thereto. Y

There are also provided a series of small neon tubes 280, 282 and 284which serve as short circuit indicators. 280 and 282 arenormallyilluminated' and are extinguished when a short circuit occurs,while 285 is-normally deenergized and lights up when a short circuitoccurs in that portion oi' the circuit to which it is connected. In theupper center part of the diagram is shown a contact block for thevarious lines to make the necessary connections.

We will now describe the operation of the system as units to be testedare applied to the test block 4. The initial position of the ratchet orrotating switch A is as shown and the screw driving means S and P areplaced in juxtaposition to the screws to be adjusted so that the trimmercondensers will be of proper capacities. The switch 206 is closed toapply the line voltage to start the motor I4 in operation and supplypower to the various portions ofthe circuit. The input terminals 222 and224 are at this time connected to a modulated radio frequency voltage ofa certainpredetermined frequencyl and having a value of approximatelyone volt. Thus the motor is in condition for driving the driving meanswhich as yet have not turned the adjusting screws, and power is appliedto all of the necessary parts of the circuit.

Switch 218 is manually depressed'momentarily and it will be obvious fromthe circuit that when this occurs point on the ratchet switch isconnected to ground. This completes a circuit through relay |83 asfollows: from the source of power indicated by the arrow, through relay|88, line 286, switch arm |60, switch contact through switch 218 toground. This causes relay |88 to raise its armature |90 and complete thecircuit through switch |90 and |92. This switch closure completes acircuit for the stepping relay |68 of the ratchet switchwhch is thenenergized through the following circuit: incoming line 204, switch 206,switch |92-I90, line 288, line 290, relay coil |68, line 292 to incomingline 202.

This ratchets the solenoid switch around until the three switch arms|60, 62 and |64 contact the next adjacent points, namely, stationaryswitch points 2, 9 and I4. At this point it is desired to point out thatwhile in its initial condition switch arm |64 while resting onstationary contact I3 applied a ground to the common connection ofresistors 260 and 258, and in moving to its new position removes suchground and causes a delayed automatic gain control voltage to be appliedto the grid of tube V1, which will be more fully described at a laterpoint inthe specification. As the switch arm |60 rests on point 2 of theswitch. it connects relay |88 now to switch |18. At the same time theswitch arm |62 in moving from point 1 to point 8 on the ratchet switchbroke the volt supply circuit through point 1 to the retracting solenoid|14 which was initially energized to keep the screw drivers S and P outof engagement with the screws to be adjusted. This initial energizingcircuit may be traced as follows: incoming line 204, switch 206, line294, switch arm |62, switch point 1, line 296, relay coil |14, line 298to incoming line 202. Thus this retracting coil for the screw drivershas been energized, but when the switch arm |62 moves to the new point8, this coil is deenergized and the screw drivers are allowed to contactthe heads of the screws which it is desired to adjust.

Let us assume that screw driver S engages the adjustable screw of thetrimmer condenser in the secondary circuit and this now is in a positionto be able to turn that screw as desired.A However, even though theshaft |04 is rotating, no driving connection has been made througheither of the bevel gears |42 or |42 to the driving gear |00. Thecircuit through switch arm |62 which now contacts point 8 is nowcompleted to one of the solenoid actuating coils for the driving meansand in this instance is relay coil |38 which is energizedthrough thefollowing circuit: line 204, switch 206, line 294, switch arm |62,switch point 8, line 300, line 302, relay coil |38, line 304, line 306to incoming line 202. This causes the coil |36 to be energized, pullingthe armature thereof upward as shown in Figure V5, and therefore causingengagement of the gear |44 with the gear |00 andcausing the screw driverS to be driven.

As previously mentioned, it is desired to run the adjusting'screw to onelimit vof its travel before starting the adjustment so that it isassured that the voltage iiow through the control circuit for adjustingthe circuit formed of the inductance and capacity in the intermediatefrequency transformer will continue to flow in one direction'until apeak has been reached. Thus the screw driver S will cause the screw tobe driven to one limit position, and as the resisting torque applied bythe screw becomes large, the clutch mechanism before referred to willallow slippage between the driving sleeve 34 and the clutch collar 92 toallow the screw driver to stop but still permit the gears to rotate.

When this occurs the clutch collar is forced axially of its shaft whichmovement closes in this instance a switch identified as |18. Thiscompletes the circuit to the solenoid |88 as follows: from ground*through switch |18, through line 388, line 3|8, switch point 2, arm |68,line 286, relay |88 to the power indicating arrow. This causes relay |88to again be energized, and, as before, such energization will complete acircuit to relay |68, which is the stepping relay for the ratchet switchA, and cause the various switch arms to be lmoved to their next adjacentswitch point which is in this instance 3, 8 and I5.

Contact arm |64 which has now moved to point I connects relay 238 toground and therefore energizes the same. This energizing circuit is fromthe source of power to the arrow on relay 238, then through 3I2, switchpoint I5, arm |64 to ground. This causes the armature members to beattracted toward the coil as shown in Figure 5, the results being todisconnect resistor 232 from resistor 3I4 and connect the same toresistor 3I6, and it also connects approximately 280 volts D. C. toinductance 3 I8 through switch |88 operated by relay |94 through thefollowing circuit: inductance 3I8, line 328, switch 246-248, line 322, a

switch I 88, line 324, relay |88, line 323, resistor 328, line 338 tothe plate 332 of the tube V5. This furnishes the Thyratron with acontinuous plate current and is in series with the relay |88 which willbe energized at such times as the Thyratron V5 draws current.

The connection of capacitor 26 to resistor 3I6 by the operation ofswitch 248-244 connects the grid circuit of the Thyratron V5 to adifferentiating circuit comprising resistor 3I6, capacity 262 andresistor 264, which provides the necessary transient voltage to the gridcircuit of the triode when the l. F. trimmer has been peaked.

In moving the contact arm |62 from point 8 to point 9 on the steppingrelay switch, the 115 volt circuit is disconnected from solenoid |38 andconnected to solenoid |48 through the following circuit: line 284,switch 286, line 294, switch arm |62, switch point 9, line 334, line336, relay coil |48, line 384, line 386 to incoming line 282. Thiscauses the armature to be drawn downwardly as shown in Figure 5 andmakes a driving connection between the gear |42 and the gear |88 whichcauses the screw driver S to be driven in the opposite direction to thatformerly applied. This then causes the screw to be backed off from oneof its limit positions, decreasing the capacity of the condenser Cs.

As this condenser is brought nearer or adjusted more nearly to acondition of resonance in the secondary circuit of the transformer, theenergy transferred therethrough will become greater and this voltageappears across the output terminals G and minus. This voltage which isdue to an audible modulation of the radio frequency being applied acrossthe terminals 222 and 224 is demodulated by one section of the 6F8Gdouble triode tube V2 and further amplified by the 6V6GT tube V3. It isthen fed into the transformer 338 which is connected to a secondtransformer 228 and mounted between the two is a small meter 238. Thetwo transformers may be replaced by a single one if the meter is notused at this point in the circuit.

The output of the signal appearing across these terminals is fed intothe half wave rectifier V4 and the rectified voltage is converted into anearly D. C. wave by the filter system comprising condenser 236, andresistors 3I4, 232 and v234, and having conductive polarity towardresistor 232. A portion of this negative voltage which appears acrossresistor 234 is applied across resistor 252 and capacity 254. As anillustration in this case, resistor 252 is about two megohms 10 andcondenserA254-approximately .5 microfarad. The voltage thereacross willtherefore take an appreciable amount of time to increase or decreaseafter the voltage has changed across resistor 234. This negativeautomatic gain control voltage which appears across condenser 254 isapplied through resistors 258 and 268 to the grid of the tube V1 anddecreases the gain of V1 kin accordance with a slightly previous voltageacross resistor 234. The resistor 268 is made variable so that it may beadjusted to give a convenient reading on the meter 238 with a standardcoil in position and peaked. All other readings will be less than that.In the step relay position during which the switch arms occupy thepositions 2, 8 and I4, it will be remembered that the trimmer condenserC's also is being changed by the screw driver S1. This causes thevoltage across the terminals G and minus to change and subsequently thevoltage across resistor 234 and eventually the automatic gain controlvoltage applied through the circuit just described to the tube V1. Whenthe contactors arrive at switch points 3, 9 and I5 by the last ratchetstep described and while the transition is made from points 2, 8 and I4to 3, 9 and I5, the automatic gain control voltage has had sumcient timeto substantially catch up with the voltage across resistor 234. It isdesired to point out that the automatic gain control is operative at allpoints except the iirst switch point where it is grounded through pointI to maintain the input of the transformer fairly constant.

Now when the switch arms are on the positions 3, 8 and I5, theregulating circuit composed of resistor 232, 234 and capacitor'236 isconnected across resistor 3I6 instead of resistor 3I4. A differentiatingcircuit or filter now consists of capacitor 262, resistor 264 and acomparatively small variable resistor 266. A change in the D. C. voltageacross resistor 3I6 will cause a current through this resistor or filtercombination to charge capacitor 262 to a new value. The direction ofthis current depends on whether the voltage across resistance 3I6increases or decreases, and the magnitude of the current depends on thetime rate and amount of change of that voltage across resistor 3I6.

The polarity is such that a decreasing voltage gives rise to adecreasing negative voltage across resistor 3I6 and a transient currentthrough resistor 264 such that the Thyratron V5 grid becomes morepositive with relation to the ground causing tube V5 to ionize when theaddition of this positive voltage to the negative bias makes its gridsufciently positive. It is also necessary to mention that the relationbetween screw driver speed, rate of change of capacity Cs to the time ofaction of the automatic gain control circuit-l is sucient so that theautomatic gain control circuit does not catch up while the screw driveris running out the screw on Cs to reach one of the extremes. However, inadjusting back to the peak adjustment and when the peak is closelyapproached, the automatic gain control circuit can catch up because thevoltage change in the region of the peak of the frequency is not asrapid as that Voltage change in approaching the peak. It should also bepointed out that as the rectified voltage approaching D. C. which issupplied to the capacity 236 becomes larger, more current is drawn bythe resistors 232, 234 and 3| 6 and the filtering action thereof is notas good as previously. The grid of tube V5 will have impressed upon it amore or less pulsating 1 l voltage. As long however as Cs is beingadjusted toward peak, there will be a considerable direct currentcomponent of transient current through resistor 264 in such a directionas to add to the negative bias on the grid to prevent V5 from ionizing.

When, however, the rate of change of voltage through the ampliiiercircuits becomes less as C5 is reaching a value to correspond to the topof the resonance peak, less additional bias is applied to the grid bythe transient current through resistor 264 and a great proportion ofthis pulsating component will pass through condenser 262 which will alsotend to cause tube ionization. it will thus be apparent that a rathercomplicated relation is obtained from screw driver speed, mechanical andelectrical relay delay, and limits of rate of change of voltage which iscaused by variation in CS and Cp with manufacturing tolerances invariation with the inductance associated with the two condensers in theI. F. transformer, the amount of filtering of the rectifled audiovoltage and the automatic gain control constant in the feedback circuit.

' Thus with the screw driver S backing oil the adjusting screw andapproaching the peak of the resonant circuit, we reach a point at whichthe rate of change of voltage ceases and at that point the tube V5 isallowed to re or ionize which action causes a flow in the plate circuitthereof which has been previously traced and includes the relay |30. Theenergization of this relay closes a pair of switches |84 and |86 whichcomplete the 115 volt A. C. circuit to relay |68 and relay |14, thefirst through the following circuit: incoming line 204, switch 20S,switch IS, line 288,V relay coil |68, line 292 back to incoming line202. This circuit energizes the stepping relay |58.- The circuit forrelay |144is as follows: incoming line '204, switch 20B, line 294, line340, switch |84, line 29E, relay coil |14, line 298, to incoming line202.

The energizatlon of relay |68'0f course causes the relay to be steppedalong one further step to change the switch arms |60, |62 and |64 tostationary switch points 4, l and I6 respectively. Also, theenergization of relay V|14 causes the screw drivers to be immediatelyretracted from engagement with either of the adjusting screws to give anaccurate peak setting. When switch arm |62 moved from switch point 9 to|0, it broke the circuit to the relay coil |40, but completed a circuitto relay coil |54 to operate the second screw driver P, which, aspreviously described, is substantially the same operation as tracedthrough with regard to the condenser known as Cs, and this screw drivertends to run down the adjusting screw in capacitor Cp until it isentirely at one Vencl of its travel as in the former case. This againcauses the Voverload clutch mechanism to slip and switch |16 to close,which again causes the energization of relay |88 to energize thestepping relay |68 and advance the various switch points one more notch,namely, to 5, and |1.

At this time the system is ready to adjust the screw in capacitor Cpback to its peak value as in the prior instance and this will cause thescrew to be backed off until such time as the tube V is allowed toionize and cause energization of the relay |80 which immediatelywithdraws the screwv drivers from contact with the adjusting screws andalso causes the step relay to actuate once more. This carries the switchcontact |02 to position I2 and in this position causes the circuit toenergize relay |10 which is the lock-in relay for the ratchet switchland upon this energization the wholeY ratchet switch mechanism isallowed to lreturn to the position initially described where it is readyfor another operation of the mechanism.

The operation of the system may be summarized as follows with respect tothe various switch positions of the automatic stepping relay A:

First position (d) Screw drivers S and P retracted by coil |14. (b)Automatic gain Acontrol circuit grounded through switch point |3. f

(c) All of the relays deenergized.

Second position Screw drivers S and P contact adjusting screws (relay|14 deenergized).

Automatic gain control circuit energized.

Driving relay |38 energized to drive adjusting screw to one extremity.

Clutch switch |18 operated to stop drive at limit of screw driver.

Third position Screw drivers still Contact the screws.

Automatic gain control circuit still energized.

Driving relay |40 now energized to reverse screw drive by screw driver Stoward peak point.

Relay energized at peak by ionization of tube V5.

Screw drivers withdrawn at zation of relay |14.

(c) once by energi- Fourth position (a) (b) (c) (a) (b) (c) sixthposition (a) Energization of unlocking relay to return whole system toits initial condition.

It will thus :be evident that the full cycle of the apparatusprovides'for the adjusting of two screws to vary capacity to resonantcircuit position, separately and independently, and an automatic returnto the initial position when that has been accomplished. Immediatelyupon reaching the resonant condition of either circuit the adjustingmeans is withdrawn so that the setting is very accurate. All that it isnecessary fcr an operator to dois to apply these transformer units tothe testing block and put them in juxtaposition to the adjusting screwdrivers, close the two main switches and the machine then takes care ofthe rest. As previously mentioned, this is only one of a number ofinstances wherein means for measuring the peak of resonant value of acircuit can be used and the applicants invention should not be limitedto theA disclosure of the specific means shown here to illustrate itsutility.V

1. In-an adjusting system for a coupling unit formed of capacity andinductance and having screwable means for adjusting the capacity to tunethe unit to a predetermined resonant frequency, a driven screw drivernormally held out of engagement with the screwable means, a stepby-steprelay switch, means for driving the screw driver in either direction,magnetic means for controlling said screw driver drive connected to saidrelay switch, and a switch controlled by longitudinal movement of thedriving means whereby the movement of the relay switch to differentpositions causes energization of the screw driver first to engage thescrewable means and then rotate the same to a limit in one direction andthen to a predetermined position in the opposite direction.

2. In an adjusting system for a coupling unit formed of capacity andinductance and having screw means for adjusting the value of thecapacity to tune the unit to a predetermined frequency, screw drivingmeans, a source of power therefor capable of driving the screw drivingmeans in either direction, magnetic means to control the direction ofrotation of the screw driving means, a slip friction clutch in thedriving means whereby when the torque exceeds a certain amount it willslip and cause longitudinal movement of one of the parts of the clutch,switch means operable by such movement, a stepby-step ratchet switchcontrolling the magnetic means for the driving means and actuating meansfor said step-by-step switch controlled by the clutch switch whereby thescrew driving means will be driven in one direction, stop, and rotate ina reverse direction automatically.

3. In an adjusting system for a coupling unit formed of capacity andinductance and having screw means for adjusting the value of thecapacity to tune the unit to a predetermined frequency, screw drivingmeans, a source of power therefor capable of driving the screw drivingmeans in either direction, magnetic means to control the direction ofrotation of the screw driving means, a slip friction clutch in thedriving means whereby when the torque exceeds a certain amount it willslip and cause longitudinal movement of one of the parts of the clutch,switch means operable by such movement, a stapby-step ratchet switchcontrolling the magnetic means for the driving means, actuating meansfor said step-by-step switch controlled by the clutch switch whereby thescrew driving means will be driven in one direction, stop, and rotate ina reverse direction automatically, and thermionic means connected to theoutput of the unit controlling the driving means to cause the same tostop further adjustment upon a peak of energy passing through the unit.

4. In an adjusting system for a tunable circuit formed of inductance andcapacity, one of which is adjustable to tune said circuit to apredetermined resonant frequency, a source of power of the desiredfrequency connected to the input of the tunable circuit, amplifyingmeans connected to the output ofthe tunable circuit, control means foradjusting the adjustable element in the tuned circuit and meansconnectiing the amplifier output to the control means and also feed backto the input of the tunable means for volume regulation.

5. In an adjusting system for a tunable circuit t121: formed ofinductance and capacity, one of which is adjustable to tune said circuitto a predetermined resonant frequencyfa source of power of vthe desiredfrequency connected to the input of the tunable circuit, amplifyingmeans connected tov the output of the tunable circuit, control means foradjusting the adjustable element in the tuned circuit, means connectingthe amplifier output tothe control means and also feed back to the inputof the tunable means for volume regulation, and delay means in the feedback means to prevent too rapid correction for volume regulation.

6. In an adjusting system for a tunable circuit formed of inductance andcapacity, one of which is adjustable to tune said circuit to apredetermined resonant frequency, driving means for adjusting saidadjustable portion in either direction, switching means to control saiddriving means vautomatically to rst drive said adjustment in onedirection and then the other, means controlled by the output of thetunable system to deenergize the driving means and a second switchingmeans between the output of the tunable means and the controlled meansto apply said outputto the controlled means only when the tunable meansis being adjusted in the second direction.

'7. In an adjusting system for a tunable circuit formed of inductanceand capacity, one of which is adjustable to tune said circuit to apredetermined resonant frequency, reversible driving means'for drivingthe adjustable means in either direction, step-by-step switching meansto control said driving means to automatically drive said adjustablemeans iirst in one direction and then in the reverse direction, controlmeans to deenergize the driving means at the desired point, anelectronic tube controlling the energization of the control means and asecond switching means controlledby the step-by-step switching meansconnected to the electronic means whereby the latter is in circuit onlyon the reverse driving of the driving means.

8. In an adjusting system, a thermionic tube in which current flowsthrough an ionized path between an anode and a cathode, operatingapparatus connected to said anode, a control electrode in said tube tocontrol the flow between the cathode and anode, a source of fluctuatingvoltage, means interconnecting said source and said control eleotrodewhose output voltage at the control electrode varies in proportion tothe rate of change of voltage at the source so that the biasing voltageat the control electrode is a function of the speed of variation ofsource voltage to control the conductive periods of the tube and theapparatus controlled thereby in proportion tothe rate of voltage change.

9. In an adjusting system, a thermionic tube in which current flowsthrough an ionized path between an anode and cathode, operatingapparatus connected to said anode, a control electrode in said tube tocontrol the flow between cathode and anode, a circuit containingcapacity and resistance in series connected between the controlelectrode and the cathode, a source of varying voltage and conductivemeans connecting said source to the circuit at a point between theresistance and capacity so that as the rate at which the voltage changesvaries, the current through the resistance will change and charge thecapacity to a different value to alter the biasing potential on thecontrol electrode and thus control the .conductive periods of the tubeand the operation of the apparatus.

, 10. In an adjusting system, a thermionic tube in which current flowsthrough an ionized path between an anode and cathode, operatingapparatus connected to said anode, a control electrode .in said tube tocontrol the flow between cathode and anode, a circuit containingcapacity and resistance in series connected between the controlelectrode and the cathode, a source of varying voltage and conductivemeans connecting said source to the circuit at a point between theresistance and capacity, an adjustable negative biasing circuit alsoconnected to the control electrode both circuits controlling the biaspotential and the conductive periods of the tube in proportion to therate of voltage change at said source.

11. In an adjusting system for a tunable circuit having inductance andcapacity, the value of at least one of which may be varied for tuningpurposes, driving means to change the value of the variable means, apower input to the tunable circuit, an amplifying output circuitconnected to the tunable circuit, means for controlling the operation ofthe driving means including a normallynon-conductive thermionic tubehaving an anode and cathode, a control element in said tube to determinethe conductive periods thereof and iilter means interconnecting theamplier output and said control element Whose output voltage isproportional to the rate of change of input voltage so that the rate ofchange of voltage in the tunable circuit controls the driving means forstopping the same'as the tuned circuit reaches peak resonance.

l2. In an adjusting systemfor a tunable circuit having inductance andcapacity, the value of atleast onev of which may be varied for tuningI16 purposes, driving means 'to change the value 'of the variable means,a power input to vthe tunable circuit, an amplifying output circuitconnected to the'tunable circuit, means for controlling the operation ofthe driving means including a normally non-conductive thermionic tubehaving an anode and cathode, a control element in said tube to determinethe conductive periods thereof, a resistance and capacity connected inseries between the cathode and control element and conductive meansinterconnecting a point between the resistance and capacity to theamplier output and an adjustable biasing means connected to the controlelement so that as the rate of change of voltage in the amplier outputchanges, the current through the resistance will change to vary thecharge on the condenser and the bias on the element and theV drivingmeans will be controlled by the rate of voltage change.

13. In an adjusting system for a tunable circuit formed of capacity andinductance, the capacity being adjustable, means for continuouslyvarying the value of the capacity, an input circuit connected to thetunable circuit having a predetermined frequency, a normallynon-conductive thermionic tube having a grid, cathode and plate, ltermeans interconnecting said grid, cathode and tunable circuit whoseoutput voltage as applied to the grid is proportional to the rate ofchange of voltage in the tunable circuit and control means for thecontinuously varying means connected to the plate of the tube so that asthe varying means adjusts the tunable circuit to resonance the rate ofvoltage variation in the output of the tuned circuit will vary, the tubewill conduct through control grid variation and the control means willbe deenergized.

MARTIN W. GAISER.

